Influence of Source of Infection and Microorganism Identified on Outcomes in Culture Negative Severe Sepsis (CNSS) Compared With Culture Positive Severe Sepsis (CPSS)

Abstract

SESSION TITLE: Infections in the ICU SESSION TYPE: Original Investigation Slide PRESENTED ON: Wednesday, November 1, 2017 at 07:30 AM - 08:30 AM PURPOSE: Many patients with severe sepsis and septic shock are found to have negative cultures. We compare influence of source of infection (SOI) on mortality, length of stay (LOS), vasopressor and mechanical ventilation requirements, and organ dysfunction between both groups. METHODS: A single-center retrospective study was performed in patients admitted to the Medical Intensive care unit or medical step-down unit, between April 2016 and December 2016. Of 400 charts reviewed, 80 patients were diagnosed with severe sepsis or septic shock. Patients were divided into CPSS or CNSS group, depending on the presence or absence of microbiological data. The SOI was delineated and associations with outcomes were evaluated. RESULTS: Commonest SOI in the CPSS group were: respiratory (37%), genitourinary/GU (29%), and gastrointestinal/GI (13%) while 8% had bacteremia without a specific source. In the CNSS group, respiratory (50%) and GU (10%) were the commonest presumed SOI while 24% had no identifiable source. There was no statistically significant difference in mortality, LOS, ventilator or vasopressor requirements with identified SOI, in both groups. However, in CPSS patients, bacteremia without a clear source was associated with more organ dysfunction (P-value 0.007) and higher morality (p-value 0.10) compared to other CPSS patients. CNSS patients with an unclear SOI had more organ dysfunction (p-value 0.05), were more likely to require vasopressors (p-value 0.04), and had a higher mortality rate (p-value 0.14) compared to other CNSS patients. We noted a significant portion of CPSS patients with multi-drug resistant (MDR) infections (39%). CONCLUSIONS: Many patients treated for severe sepsis and septic shock are deemed “culture negative” in the absence of microbiological data. Although many patients with CNSS have a presumed SOI, the source often remains unclear. We noted that CNSS is associated with increased mortality and organ dysfunction, with higher vasopressor requirements when the SOI is unclear. There was no statistically significant difference between variables when presumed source or confirmed SOI were compared between CPSS and CNSS. We note a high rate of MDR infections in the CPSS group. This supports the concept of antibiotic stewardship. CLINICAL IMPLICATIONS: CNSS with an unclear SOI is a sub-segment of patients at high risk for poorer outcomes. CPSS patients have a high proportion of MDR infections, raising concerns regarding management of such infections and the need for effective antibiotic stewardship. DISCLOSURE: The following authors have nothing to disclose: Jessica Gupta, Viren Kaul, Saumya Easaw, Lisa Alex, Martin Warshawsky No Product/Research Disclosure Information